View Full Version : SASI/SCSI on my CRDS 68 system

January 29th, 2015, 01:50 PM
Hi All;
I do not know for sure.. But for now and to test my Theory.. That the CC-1 Board is OK and its my SMS Omti 20D is what is Bad..
The signals that come off of the CC-1 Board are SASI/SCSI Signals and comparing them to what I have in my book..
"The Hard Disk Technical guide" they are the same Except for two signals mine doesn't have the "Terminator Power and the --ATN Attention signal"..
The Terminator Power can be wired in, Can I ignore the --Atn signal ??
So, can I hook up and old SCSI Hard Disk Drive, directly to my system and NOT Blow any more up than maybe done in the Past ??
And if I can find any or If they made any SCSI Floppies (Apple) that I could use these in my system to at least get it somewhat going..
I know I would need to copy using my Altair with Andrew's and John's Z80 and Floppy Controller Board, to copy from the 8" diskettes to the 3.5" diskettes, and then hopefully they would be readable by the SCSI floppy drives..
Since I can find No information on the SMS Omti 20 Series, there is the Omti 5200 which is a later Board and its internals are different, it (the 5200) uses a Z8 and the 20 series uses a 2901..
I have the Manual for the Omti 5200 from Bitsavers, but there is nothing on the 20 series..
Any Ideas ??


January 29th, 2015, 03:47 PM
You should be able to get by without the ATN signal, but don't quote me on that. It's used when multiple initiators are on the bus. Z8 also on the OMTI 7000 board that I've got.

The manual for the 5x00 (http://www.textfiles.com/bitsavers/pdf/sms/microcontroller/MC555D_SMS_The_Microcontroller_System_Description_ 1975.pdf) says that the interface is the same as the 20 (see p. 2-6).

January 29th, 2015, 04:15 PM
Hi All;
Thank You Chuck for Your Answer..
""The manual for the 5x00 says that the interface is the same as the 20 (see p. 2-6)."" Yes, I already read that, But what I would like is a schematic or block Diagram, to help me find the Problem with my Omti 20, I know I could Substitute a Omti 5200 for the Omti 20D, and they did that After August 1985, So my machine was made prior to that date.. And the Software will work with either board..
But I don't know where I would get an Omti 5200 for that matter.. Or anything that I could substitute in place of the Omti 5x00 series.. I know Xebex made conversion Boards, and I might have a Bad one of those somewhere around, but that won't help either..
They used in these machines Omti 20D, Omti 5200 and Omti 5400 depending on the configuration.. Hard disk and either floppy or 1/4 inch tape..


January 30th, 2015, 10:54 AM
Hi All;
I tried a Scsi Hard drive, and it may have Killed my CC-1 Board..
Anyway, it shows an Error that I have not had before..
So, I need a VersaBus Extender Card..


January 30th, 2015, 11:28 AM
Ouch. Sorry to hear that, but I don't know how the drive could toast your CC-1--unless there's something wrong with the drive.

January 30th, 2015, 12:31 PM
Hi All;
Well Chuck, You will be Glad to hear, that I found the problem.. Thank You for Your Concern..
What it turned out to be, after taking the back end all apart, and inserting the Cards one at a time in the top slot, and finding out that the CC-1 Card, was not Cut Correctly, and so it looked like it was plugged in, but it wasn't..
I Re-filed the sides next to the fingers, so it will go in straight and all the way in as well..
I even plugged in the Drive, and the System stated --
Booting cb0..
SMS 5000 controller..
Invalid Volume ID..
Since it is an old Apple Drive with Apple Software on it, I would be Very Surprised, if it said it was Ok..
I still need to find a way to copy from the Floppies to this Hard Drive..
That also tells me that the CC-1 Board is OK, and its the Omti 20D that is Bad..


January 30th, 2015, 02:21 PM

I assume that you need to boot from floppy and run some sort of configuration program? If it's just a matter of transferring sector-by-sector, it'd be a simple matter of hooking up a Linux box to your drive and dd-ing the floppy images over.

January 30th, 2015, 03:23 PM
Hi All;
Thank You Chuck for Your Suggestions..
But it may not be that simple, for a couple of Reasons..
The Floppies are 8" Double Sided Double Density.. And I Don't have an easy way to Read them.. And Then, Yes probably I would need to Run the bootable system to Set up the Hard Drive.. Before it could be copied, from the floppies to the Hdd..
But, there is the option you suggested "" If it's just a matter of transferring sector-by-sector, it'd be a simple matter of hooking up a Linux box to your drive and dd-ing the floppy images over. ""
So I can try my 8" to 51/4" converter from Dbit, but I don't know If it will work with DSDD floppies..
I can also use my Altair using Andrew's and John's ZFDC board, but I still wouldn't know how to transfer the content to the PC, and then to the SCSI Hard Disk..
Any Ideas are welcome !!!


February 2nd, 2015, 12:35 PM
Hi All;
I have started to take out some of the Ic's that are connected to the SCSI Bus, and I hope that the problem is in this interface or in the interface to the Floppy, which is mostly about 3 other Ic's, a 74LS273 and two 74LS240's..
The Ic's that I have taken out are 4- each 74LS642's and two each 7438's..
The 7438's I have, not sure about the 74LS642's, might have to use something else..
I will need to wait until, I get some more sockets and some solder, probably tomorrow sometime..
Here is a picture..



February 2nd, 2015, 02:16 PM
The 642s are pretty specific to SCSI applications, but Mouser claims to have them in stock.

February 2nd, 2015, 02:28 PM
Hi All;
Chuck, yeah, I know, but at least on the ones, I saw, I about had a heart attack, ($8. something each).. Anyway I found some on Ebay for alot better price, ($1.95 each) they had 10 of them so I got them all..